good small cheap compatible computer?

hi all,
i am new to CNC machine and looking to build my own.
been looking at a few options, one was to go with planetCNC and their usb boards.
but that is looking to expensive. so i though i might try my luck with linuxCNC, the only problem i have is finding a computer to run it.
Does anyone know if there are any tiny computers that is known to support it or any computers that are available on ebay or some store i could order and they arn't to costy. I am a bit worried about trying to source a computer only to find it wont work.

Hi

If you are software stepping you need decent latency.

This is a list compiled by members of computers and motherboards that work and the latency figures they give.
wiki.linuxcnc.org/cgi-bin/wiki.pl?Latency-Test

Beware of going for tiny PCs. They tend to have very little expansion potential, sometimes no PCI slots just 1 PCIe and one PCIe mini, no parallel port and some USB ports.

regards

Hi,

There is a version of LinuxCNC (MachineKit) that runs on the beaglebone black (BBB) processor board. That board costs $55.00 and is about the size of an altoids tin (so pretty tiny). You might want to to get an expansion board (known as a 'cape') to gain access to the control signals. You can find a list of capes here:

blog.machinekit.io/p/hardware-capes.html

Step generation is controlled by the extra processor units (PRU) built in to the ARM processor on the BBB.

MachineKit running on BBB is "bleeding edge" software, so if you are looking for some very stable I wouldn't recommend it. But if you are looking to put together your own small system, it is an interesting place to start.

I make a simple plug in board for the BBB that has a DB25 connector on it that gives the basic functions of a parallel port (see Xylotex BeagleCNC BBB_DB25) in the list on the link I provided above.)

If you are in to electronics, you could also make your own cape. The specs on the BBB or open, and the HALand other setup files allow a pretty wide range of configuration for the BBB.

More information on the BBB can be found here:

beagleboard.org/black

If you do get interested in running that board, more information about MachineKit can be found here:

groups.google.com/forum/#!forum/machinekit

Jeff

thanks for your replies.
i was very interested in the BBB, but thought i might wait a while longer until it is stable.

i actually found this old computer someone is selling... would there be any reason to worry with this computer running it?

Intel Pentium Dual Core E6300 2.80GHZ Processor / 3.00GB DDR2 Ram / 200GB hard drive / Nvidia GeForce 8400 GS Graphic Card / DVD + RW burner / 320W Power Supply

the guy also has an old intel pentium 4 2.8 ghz processor 1 gig ram 80 ghd nvidea card

i read somewhere that it can be better to run the old processors with linuxCNC.

would anyone recommend me getting this old computer to run it?

thanks for any help too guys. really appreciate it.

Hi

The problem with latency is that it varies from computer to computer and between chipsets on the same computer ranges.

I have 2 x 2.8MHz P4s in my workshop which work fine, but they are a specific make and model which has a specific chipset ( they are on the page I posted, Fujitsu-Seimens )

If this guy is close enough, can you burn the live CDs and try them by booting into the CD and testing latency?
That is the best test of all.

The problem these days with the P4s, is that support for the Ubuntu 8.04 based distro has finished.
Therefore there is no easy update path beyond Linuxcnc ver 2.5.4, unless you build the source yourself.
Even then, the libraries required are starting not to be available in packages for 8.04, so it is not straight forward

They tend to run badly on the Ubuntu 10.04 based distro, I have not tested the Wheezy based distro.
I use Wheezy but with a home brew UP kernel.

You might be better off with the E6300, but having a nvidia video card is not a plus where Linuxcnc is concerned

You either need to get something you know has good latency, or take a punt and if it does not work out, be prepared to put it back on Ebay and try another

regards

I have bought for this purpose an Asrock Q1900M with a 4* Celeron 2Ghz SOC. It cost some 70$, I tested latency and get around 7000, with a 2*Pentium 3GhZ S775 I reached only 20.000

The Biostar A68N-5000 is also a decent fanless Mini ITX MB that works well with Linuxcnc

Yes, parallel and serial are on a internal connector. 1 PCI-E16 + 2PCI-E1 and 2 Sata,

But at the Moment, I can't determine, if it's really good, because I haven't yet any communication with the 7i76E Lan Board.
It has nearly the same features like PCW's Biostar A68N-5000, a little bit faster Prozessor, but the graphics engine is a bit slower.